<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>windows::basic_stream_handle::async_write_some</title>
<link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<link rel="home" href="../../../boost_asio.html" title="Boost.Asio">
<link rel="up" href="../windows__basic_stream_handle.html" title="windows::basic_stream_handle">
<link rel="prev" href="async_read_some.html" title="windows::basic_stream_handle::async_read_some">
<link rel="next" href="basic_stream_handle.html" title="windows::basic_stream_handle::basic_stream_handle">
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td>
<td align="center"><a href="../../../../../index.html">Home</a></td>
<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="async_read_some.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../windows__basic_stream_handle.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="basic_stream_handle.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.reference.windows__basic_stream_handle.async_write_some"></a><a class="link" href="async_write_some.html" title="windows::basic_stream_handle::async_write_some">windows::basic_stream_handle::async_write_some</a>
</h4></div></div></div>
<p>
          <a class="indexterm" name="boost_asio.indexterm.windows__basic_stream_handle.async_write_some"></a> 
Start
          an asynchronous write.
        </p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <a class="link" href="../ConstBufferSequence.html" title="Constant buffer sequence requirements">ConstBufferSequence</a><span class="special">,</span>
    <span class="keyword">typename</span> <a class="link" href="../WriteToken.html" title="Write token requirements">WriteToken</a> <span class="special">=</span> <span class="identifier">default_completion_token_t</span><span class="special">&lt;</span><span class="identifier">executor_type</span><span class="special">&gt;&gt;</span>
<a class="link" href="../asynchronous_operations.html#boost_asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type"><span class="emphasis"><em>DEDUCED</em></span></a> <span class="identifier">async_write_some</span><span class="special">(</span>
    <span class="keyword">const</span> <span class="identifier">ConstBufferSequence</span> <span class="special">&amp;</span> <span class="identifier">buffers</span><span class="special">,</span>
    <span class="identifier">WriteToken</span> <span class="special">&amp;&amp;</span> <span class="identifier">token</span> <span class="special">=</span> <span class="identifier">default_completion_token_t</span><span class="special">&lt;</span> <span class="identifier">executor_type</span> <span class="special">&gt;());</span>
</pre>
<p>
          This function is used to asynchronously write data to the stream handle.
          It is an initiating function for an <a class="link" href="../../overview/model/async_ops.html" title="Asynchronous Operations">asynchronous
          operation</a>, and always returns immediately.
        </p>
<h6>
<a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.h0"></a>
          <span class="phrase"><a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.parameters"></a></span><a class="link" href="async_write_some.html#boost_asio.reference.windows__basic_stream_handle.async_write_some.parameters">Parameters</a>
        </h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">buffers</span></dt>
<dd><p>
                One or more data buffers to be written to the handle. Although the
                buffers object may be copied as necessary, ownership of the underlying
                memory blocks is retained by the caller, which must guarantee that
                they remain valid until the completion handler is called.
              </p></dd>
<dt><span class="term">token</span></dt>
<dd>
<p>
                The <a class="link" href="../../overview/model/completion_tokens.html" title="Completion Tokens">completion
                token</a> that will be used to produce a completion handler, which
                will be called when the write completes. Potential completion tokens
                include <a class="link" href="../use_future.html" title="use_future"><code class="computeroutput"><span class="identifier">use_future</span></code></a>, <a class="link" href="../use_awaitable.html" title="use_awaitable"><code class="computeroutput"><span class="identifier">use_awaitable</span></code></a>, <a class="link" href="../yield_context.html" title="yield_context"><code class="computeroutput"><span class="identifier">yield_context</span></code></a>, or a function
                object with the correct completion signature. The function signature
                of the completion handler must be:
              </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span>
  <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&amp;</span> <span class="identifier">error</span><span class="special">,</span> <span class="comment">// Result of operation.</span>
  <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span> <span class="comment">// Number of bytes written.</span>
<span class="special">);</span>
</pre>
<p>
                Regardless of whether the asynchronous operation completes immediately
                or not, the completion handler will not be invoked from within this
                function. On immediate completion, invocation of the handler will
                be performed in a manner equivalent to using <a class="link" href="../async_immediate.html" title="async_immediate"><code class="computeroutput"><span class="identifier">async_immediate</span></code></a>.
              </p>
</dd>
</dl>
</div>
<h6>
<a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.h1"></a>
          <span class="phrase"><a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.completion_signature"></a></span><a class="link" href="async_write_some.html#boost_asio.reference.windows__basic_stream_handle.async_write_some.completion_signature">Completion
          Signature</a>
        </h6>
<pre class="programlisting"><span class="keyword">void</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">)</span>
</pre>
<h6>
<a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.h2"></a>
          <span class="phrase"><a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.remarks"></a></span><a class="link" href="async_write_some.html#boost_asio.reference.windows__basic_stream_handle.async_write_some.remarks">Remarks</a>
        </h6>
<p>
          The write operation may not transmit all of the data to the peer. Consider
          using the <a class="link" href="../async_write.html" title="async_write"><code class="computeroutput"><span class="identifier">async_write</span></code></a> function if you need
          to ensure that all data is written before the asynchronous operation completes.
        </p>
<h6>
<a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.h3"></a>
          <span class="phrase"><a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.example"></a></span><a class="link" href="async_write_some.html#boost_asio.reference.windows__basic_stream_handle.async_write_some.example">Example</a>
        </h6>
<p>
          To write a single data buffer use the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput"><span class="identifier">buffer</span></code></a> function as follows:
        </p>
<pre class="programlisting"><span class="identifier">handle</span><span class="special">.</span><span class="identifier">async_write_some</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</span><span class="special">,</span> <span class="identifier">size</span><span class="special">),</span> <span class="identifier">handler</span><span class="special">);</span>
</pre>
<p>
          See the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput"><span class="identifier">buffer</span></code></a>
          documentation for information on writing multiple buffers in one go, and
          how to use it with arrays, boost::array or std::vector.
        </p>
<h6>
<a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.h4"></a>
          <span class="phrase"><a name="boost_asio.reference.windows__basic_stream_handle.async_write_some.per_operation_cancellation"></a></span><a class="link" href="async_write_some.html#boost_asio.reference.windows__basic_stream_handle.async_write_some.per_operation_cancellation">Per-Operation
          Cancellation</a>
        </h6>
<p>
          This asynchronous operation supports cancellation for the following <a class="link" href="../cancellation_type.html" title="cancellation_type"><code class="computeroutput"><span class="identifier">cancellation_type</span></code></a>
          values:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">cancellation_type</span><span class="special">::</span><span class="identifier">terminal</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">cancellation_type</span><span class="special">::</span><span class="identifier">partial</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">cancellation_type</span><span class="special">::</span><span class="identifier">total</span></code>
            </li>
</ul></div>
</div>
<div class="copyright-footer">Copyright © 2003-2025 Christopher M.
      Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
</div>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="async_read_some.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../windows__basic_stream_handle.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="basic_stream_handle.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>
